The purpose of the invention is to provide an improved apparatus for and method of detecting ions in a hydrogen flame detector. The hydrogen flame detector is an analytical instrument typically used for chemical analysis at the output port of an instrument such as a gas chromatograph. In the instrument, hydrogen is burned in the vicinity of two electrodes. An unknown chemical introduced into the flame is ionized, thereby causing the flow of a small ionic current between the electrodes. As the quantity or the composition of the unknown chemical changes, a variation in this ionic current is detected and correlated with the chemical changes.
The ionic currents are measured by any of a number of electrometer-type devices. The measurement precision of each of these devices, however, is limited by several physical factors. Photoemission, thermoelectric effects, instabilities in flame temperature, and other effects, for example, cause instabilities which mask small variations introduced by the chemicals under test. These limiting factors are overcome by the invention described herein.